Sheet-like materials for use in the containment and protection of various items, as well as the preservation of perishable materials such as food items, are well known in the art. Such materials can be utilized to wrap items individually and/or can be utilized to form a closure for a semi-enclosed container.
One class of such materials in common use today comprises those of polymeric composition formed into a thin, conformable web commonly supplied in rolled form. Common examples of such materials are polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and polyethylene (PE) sheet materials. These materials exhibit a clinging character on at least one surface due to the properties of the polymeric materials they are formed from and/or additives such as plasticizers, tackifiers, etc., such that they may be folded or wrapped around an item such that they cling to the item and/or to themselves. The clinging character of such materials also permits their use in combination with semi-enclosed rigid, semi-rigid, or flexible containers to provide a fully enclosed container structure. The barrier properties of many such materials, particularly their oxygen, moisture/moisture vapor, and odor barrier properties, provide the desired preservation characteristics for perishable items such as food items and/or items which oxidize or otherwise degrade more rapidly with continued exposure to environmental conditions.
While these materials have achieved a certain level of acceptance, where the material is supplied in the form of a continuous roll in a dispensing carton or apparatus, difficulty is often encountered locating and isolating the current end portion of the rolled web in order to start the dispensing operation. In order to address this issue, a number of methods of identifying and/or isolating the current end of the rolled web have been developed (tabs, colors, end-grasping dispenser features, etc.) which have achieved varying levels of success. Irregardless of the issue of handling the end of the rolled web, the tendency of the material to cling to itself also increases the dispensing force required to unroll the web and tangentially separate the dispensed portion and, if excessive, can lead to a phenomenon known as "roll blocking" wherein the dispensing force to unroll becomes excessive. Roll blocking can also cause excessive dispensing forces which can lead to longitudinal tearing of the web in the roll direction, leading the user to dispense a narrower, unevenly-torn portion of the rolled web. In addition, users frequently encounter situations wherein the material clings to itself prematurely (i.e., before contacting the desired bonding surface), thus necessitating either the manual disengagement of the clinging portion(s) and/or discarding of the material in favor of a new portion.
Another difficulty which may be encountered is the failure of the material to adhere to itself and/or the desired target surface sufficiently to form an airtight seal either from the outset or after a period of handling of the container or wrapped item. If such materials cannot form a seal with barrier properties at least as great as those of the material itself, the full potential of such materials in use as a storage wrap cannot be realized as the seal becomes the weakest link in terms of containerization. Accordingly, some users employ additional securement features such as rubber bands, tapes, etc. Wrinkles in the material where it clings to itself or a target surface can leave small channels in the region between the material and the opposing surface, thereby causing a failure to achieve the desired seal quality for preservation of perishable items. Some users attempt to address seal quality shortcomings by double- or triple-wrapping the desired item to form a tortuous labyrinth seal path of increased length.
Also, because the materials "cling" to themselves and other surfaces, i.e., exhibit an attraction or affinity for the material rather than an adhesive bond, their affinity for a complementary surface is highly dependent upon material characteristics such as chemical composition, electrical conductivity, surface energy, surface finish, etc. Therefore, such materials leave room for improvement both in ease of use as well as ability to form an adequate seal for preservation of perishable items. In many instances, the plasticizers, tackifiers, and other cling additives utilized to provide the cling properties of such materials may also introduce undesirable attributes such as odor to the finished web and/or may introduce environmental concerns.
Another class of materials in common use today comprises thin, conformable webs of various compositions commonly supplied in individual sheet or rolled form. Common examples of such materials include aluminum foil, coated (waxed, etc.) paper, etc. These materials exhibit no adhesive or cling character on either surface, instead relying upon the dead-fold characteristics of the materials they are formed from such that they may be folded or wrapped around an item and retain their folded or wrapped shape. The ability of these materials to maintain their folded or creased shape also permits their use in combination with semi-enclosed rigid, semi-rigid, or flexible containers to provide a fully enclosed container structure. The barrier properties of many such materials, particularly their oxygen, moisture/moisture vapor, and odor barrier properties, provide the desired preservation characteristics for perishable items such as food items and/or items which oxidize or otherwise degrade more rapidly with continued exposure to environmental conditions.
While these materials have achieved a certain level of acceptance, users frequently encounter situations wherein the material fails to remain sufficiently folded and engaged with itself and/or a semi-enclosed container to adequately enclose and preserve the item (i.e., the folds tend to unfold with time or mechanical disturbance), thus necessitating either refolding and external securement of the folded portion(s) and/or discarding of the material in favor of a new portion and re-accomplishing the wrapping process. In some instances, such materials may also be constructed of very thin materials in order to achieve the desired degree of conformability. This may result in the material having insufficient tensile properties to dispense from a roll without longitudinal tearing of the web in the roll direction, leading the user to dispense a narrower, unevenly-torn portion of the rolled web.
Another difficulty which may be encountered is the failure of the material to form an adequate seal where folded either from the outset or after a period of handling of the container or wrapped item. If such materials cannot form a seal with barrier properties at least as great as those of the material itself, the full potential of such materials in use as a storage wrap cannot be realized as the seal becomes the weakest link in terms of containerization. Accordingly, some users undertake to employ additional securement features such as rubber bands, tapes, etc. Wrinkles in the material where it meets itself or a target surface can leave small channels in the region between the material and the opposing surface, thereby causing a failure to achieve the desired seal quality for preservation of perishable items. Some users attempt to address seal quality shortcomings by double- or triple-wrapping the desired item to form a tortuous labyrinth seal path of increased length.
The effective fold radius of these materials is also a factor in determining their suitability for forming an effective seal, as the fold radius of some materials (paper based, etc.) is determined by such material properties as fiber length. A fold radius which is too large will generally render such a material unsuitable for forming an effective seal. In addition, due to the fact that most such dead-fold type materials are opaque, the condition and/or type of items contained in such a packaging system are also obscured from view, necessitating un-wrapping and re-wrapping the items to permit inspection.
Such materials, due to their lack of any adhesive properties, are also difficult to effectively employ in the preservation of perishable items in combination with a semi-enclosed container where the container provides no physical or mechanical engagement features (such as a conventional bowl) around which to fold the material to effect a mechanical labyrinth-type seal between the material and the container. Therefore, such materials leave room for improvement both in ease of use as well as ability to form an adequate seal for preservation of perishable items.
Accordingly, it would be desirable to provide an improved storage wrap material which exhibits convenient, efficient dispensing by a user by having a readily located end portion and a comparatively low unrolling force.
It would also be desirable to provide such a material which is easily handled and manipulated by a user during the enclosure process yet forms an adequate seal with a wide variety of materials and surfaces to effectively preserve perishable items.
It would also be desirable to provide such a material which is capable of being utilized in various modes of item containment and preservation as desired by a user, such as independent use and/or use in combination with a semi-enclosed container, in efficient fashion by substantially reducing if not eliminating the need for double-wrapping and/or additional securement features.
It would further be desirable to provide such materials which are capable of being readily manufactured, stored, and re-used as desirable for both economic and environmental efficiency.